1. Field of the Invention
The present invention pertains to fiber optic connectors. The invention more particularly concerns a fiber optic connector which enables a user to replace a physical contact, fiber optic connector with an expanded beam, fiber optic connector.
2. Discussion of the Background
Fiber optic connectors and cables are known in the art. Typically, a fiber optic cable is terminated at each end by a respective fiber optic connector. At least two categories of fiber optic connectors exist and include physical contact connectors and expanded beam connectors. In practice, a fiber optic cable terminated with physical contact connectors will only connect to other fiber optic cables which are also terminated with physical contact connectors. Likewise, in practice, a fiber optic cable terminated with expanded beam connectors will only connect to other fiber optic cables which are also terminated with expanded beam connectors.
Physical contact connectors are characterized as such since one end of a ferrule of a first fiber optic connector physically contacts one end of a ferrule of a second fiber optic connector. Light exiting the core of the optical fiber held within the ferrule of the first fiber optic connector is then immediately introduced into the core of the optical fiber held within the ferrule of the second fiber optic connector. If the two cores are misaligned by more than a whole number of diameters of the core of the optical fiber, then most of the optical power is not exchanged from the core of the first fiber optic connector to the core of the second fiber optic connector. If a piece of debris is caught between the core of the first fiber optic connector and the core of the second fiber optic connector, then it is probable that no optical power will be exchanged from the core of the first fiber optic connector to the core of the second fiber optic connector, assuming that the debris has a size which is approximately the same size or larger than the size of the core of one of the optical fibers. Examples of physical contact connectors are set forth in U.S. Pat. Nos. 5,481,634, and 6,234,683. U.S. Pat. Nos. 5,481,634, and 6,234,683 are hereby incorporated herein by reference. Over time, the industry has utilized many physical contact, single fiber, fiber optic connectors as standards or styles, such as the LC, FC, ST, and SC fiber optic connectors.
FIG. 1 is a perspective view of one type of physical contact, single fiber, fiber optic connector 10. The fiber optic connector 10 includes a ferrule 12. Also shown is an optical cable 16. The fiber optic connector 10 generally conforms to the LC-style fiber optic connector. The ferrule 12 conforming to the LC-style has an outside diameter of approximately 1.25 millimeters. FIG. 2 is an exploded, perspective view of the fiber optic connector 10 of FIG. 1. Further shown in FIG. 2 is the optical fiber 14 of the optical cable 16. Also, the ferrule 12 is more clearly shown. FIG. 3 is a partial cross-sectional side view of two fiber optic connectors 10, 20, and two receptacles 18, 19. Fiber optic connector 10 is shown in partial cross-section, but the ferrule 12 is shown in side view. The other fiber optic connector 20 and the two receptacles 18, 19 are shown in cross-section. Receptacle 18 is attached to receptacle 19. Each receptacle 18, 19 is adapted to receive a fiber optic connector that conforms to the LC-style. Also shown is the physical contact between the ferrule 12 of the one fiber optic connector and the ferrule 22 of the other fiber optic connector 20.
FIG. 4 is a perspective view of three different types or styles of physical contact, single fiber, fiber optic connectors. A flat panel 24 contains three openings. The first opening is a receptacle 26 which accommodates two SC-type fiber optic connectors 32, 33, the second opening is a receptacle 28 which accommodates two FC-style fiber optic connectors 34, 35, and the third opening is a receptacle 30 which accommodates two ST-style fiber optic connectors 36, 37. The ferrules of the fiber optic connectors 32, 33, 34, 35, 36, 37 have an outside diameter of approximately 2.5 millimeters. FIGS. 1, 2, 3, and 4 are illustrations derived from figures found in U.S. Pat. No. 5,481,634.
Expanded beam connectors are characterized as such since the optical fiber of the fiber optic cable is mated with a lens, typically a ball lens. The expanded beam fiber optic connector holds the terminated end of the optical fiber adjacent to the lens. When optical power exits the core of the optical fiber, the optical power then enters the lens, and then eventually exits the lens. The lens causes the optical power, or light, to diverge or expand before the optical power exits the fiber optic connector. If a second expanded beam fiber optic connector is attached to the first expanded beam fiber optic connector, then, after the optical power exits the first expanded beam fiber optic connector in the expanded state, the optical power will enter the second expanded beam fiber optic connector. The optical power will enter the lens of the second expanded beam fiber optic connector and then exit the lens. The lens of the second expanded beam fiber optic connector causes the optical power to converge. The focal point of the lens of the second expanded beam fiber optic connector is centered at the core of the optical fiber of the second fiber optic cable so that substantially all of the optical power exiting the lens enters the optical fiber. If the two cores are misaligned by less than a whole number of diameters of the core of the optical fiber, then most of the optical power is exchanged from the core of the first fiber optic connector to the core of the second fiber optic connector. If a piece of debris is caught between the lens of the first fiber optic connector and the lens of the second fiber optic connector, then it is probable that some of the optical power will be exchanged from the core of the first fiber optic connector to the core of the second fiber optic connector, assuming that the debris has a size which is approximately the same size or larger than the size of the core of one of the optical fibers but is smaller than the diameter of the expanded beam. Examples of expanded beam connectors are set forth in U.S. Pat. No. 5,247,595. U.S. Pat. No. 5,247,595 is hereby incorporated herein by reference.
FIG. 5 is a cross-sectional side view of an expanded beam connector 40 that includes an optical fiber 41 and a lens 42. FIG. 6 is a cross-section side view of two expanded beam connectors 40, 43 which are readied for optical communication with one another. FIGS. 5, and 6 are illustrations derived from figures found in U.S. Pat. No. 5,247,595.
Another type of expanded beam device exists. FIG. 7A is a side view of an optical fiber 50 which includes a collimator portion. The collimator portion includes a mode widening segment 52 so as to expand the light transmitted through the optical fiber as the light travels from a single mode fiber portion 51 and into and through the mode widening segment 52 and an expansion holding segment 53 which keeps the expanded light in an expanded state. However, the collimator portion may include only the mode widening segment 52. FIG. 7A is an illustration derived from figures in U.S. Pat. No. 7,155,096. U.S. Pat. No. 7,155,096 is hereby incorporated herein by reference. The segment 52 of the optical fiber which expands the transmitted light is also known as a modified mode field diameter (MFD) which expands the beam size. The MFD segment 52 may be fused or welded onto an optical fiber 50 or an optical fiber 50 can be doped so as to form a MFD segment 52. As compared to the spherical ball lens in FIG. 5, the MFD segment 52 of the optical fiber 50 is approximately the same diameter as the diameter of the single mode portion 51 of the optical fiber 50.
Note that the tip of the optical fiber 50 can have various shapes. FIG. 7B is a cross-sectional side view of an optical fiber 50 where the MFD segment 52 includes a diameter widening portion which acts as a magnifier. Also, as another example, FIG. 7C is a cross-sectional side view of the optical fiber 50 where the MFD segment 52 includes a generally spherically shaped portion.
Accordingly, there is a need for a device which incorporates the advantages of the expanded beam fiber optic connector into the well received package size of the known physical contact, fiber optic connectors.